BENGALURU: Had the July 30-launched NASA-ISRO Synthetic Aperture Radar (NISAR) satellite been operational now, several lives would have been saved through evacuation ahead of the killer cloudburst and flash floods that almost wiped out Dharali village in Uttarkashi district of Uttarakhand on Tuesday afternoon.
The 2,393 kg NISAR’s unique dual-band synthetic aperture radar (SAR) will employ advanced, novel SweepSAR technique, to provide high resolution and large swath imagery, and will scan the entire globe to provide all-weather, day & night data at 12-day intervals. NISAR can detect even small changes in the Earth’s surface such as ground deformation, storm characterization, ice sheet movements and sea ice classification, changes in soil moisture, mapping & monitoring of surface water resources, vegetation dynamics, shoreline monitoring and disaster response.
NISAR, carrying the dual-band SAR involving L- & S-Band SAR, is a global, microwave imaging satellite capable of acquiring fully polarimetric and interferometric data. While the S-band radar system, data handling and high-speed downlink system, the spacecraft and the launch system are developed by ISRO, the L-band radar system, high speed downlink system, the solid-state recorder, GPS receiver, the 9-metre boom hoisting the 12-metre unfurlable reflector, are delivered by NASA.
A senior official from the regional centre of ISRO’s National Remote Sensing Centre – which will collect the S-Band data that NISAR’s radar will capture and relay – said, “Although our work of analyzing the satellite images will increase, getting accurate advance information will be crucial. While the existing satellites and various government departments do share advanced information and alerts, the NISAR data will be several steps ahead. It will share better quality and high resolution images of the same location – irrespective of weather and sunshine – of the same location, twice every 12 days. This will help in knowing dangers and issuing alerts to the district and village administrations in advance.”
The objective of the $1.5 billion NISAR mission is to provide information that will help in disaster management, infrastructure improvement, responding to climate changes and avert casualties. It will start relaying satellite images captured from the sun-synchronous polar orbit 90 days after it launched.
In these 90 days, the NISAR mission is being dedicated to commissioning, or in-orbit checkout (IOC), to prepare NISAR for science operations. Commissioning is divided into sub-phases of initial checks and calibrations of mainframe elements followed by NASA’s Jet Propulsion Laboratory (JPL) engineering payload and instrument checkout. NISAR’s science operations phase will begin at the end of commissioning and will extend till the end of its five-year mission life.
The NASA’s Alaska Satellite Facility Distributed Active Archive Centre will handle 85 terabytes data on a daily basis, NASA’s JPL will receive 35 terabyte, ISRO’s NRSC Shadnagar centre will receive eight terabyte of data, while India’s Antarctica Centre will receive crucial data on a daily basis.
The NISAR will bring in better understanding and better quality of data, which will be crucial in averting tragedies. The NISAR information can also be superimposed on the data and the images obtained from other sources for even better understanding and implementation, the NRSC official said.
Rajesh NL, Director, Karnataka State Remote Sensing and Application Centre (KSRSAC), said the information on the soil moisture to the depth of 10-15cms will help understand and analyse how predicted rainfall could impact existing locations, which in turn will help in issuing advance warnings to prevent casualties or even crop loss.
Prof Sekhar Muddu, Department of Civil Engineering, Indian Institute of Science (IISc), said there is a list of vulnerable places prone to landslides and other disasters. Now when the soil moisture saturation, density of clouds and the wind flow information with exact geo-coordinates will be available (through NISAR), then better planning and management can be done, considering technological interventions and identification of weak spots ahead of time are essential.